JP5910004B2 - Copper alloy for electronic equipment, method for producing copper alloy for electronic equipment, copper alloy plastic working material for electronic equipment and electronic equipment parts - Google Patents

Description

  The present invention relates to a copper alloy for electronic devices suitable for electronic device components such as terminals, connectors, relays, lead frames, etc., a method for producing a copper alloy for electronic devices, a copper alloy plastic working material for electronic devices, and an electronic device component It is about.

  2. Description of the Related Art Conventionally, along with downsizing of electronic devices and electrical devices, electronic device parts such as terminals, connectors, relays, and lead frames used in these electronic devices and electrical devices have been reduced in size and thickness. . For this reason, a copper alloy excellent in springiness, strength, and electrical conductivity is required as a material constituting electronic device parts. In particular, as described in Non-Patent Document 1, a copper alloy having high proof strength is desirable as a copper alloy used as a component for electronic equipment such as terminals, connectors, relays, and lead frames.

Here, as a copper alloy used as a component for electronic equipment such as terminals, connectors, relays, and lead frames, for example, as shown in Patent Document 1, phosphor bronze containing Sn and P is widely used.
As other alloys, a Cu—Mg alloy described in Non-Patent Document 2, a Cu—Mg—Zn—B alloy described in Patent Document 2, and the like have been developed.

Japanese Patent Laid-Open No. 01-107943 Japanese Patent Laid-Open No. 07-018354

Yukiya Nomura, “Technical Trends of High Performance Copper Alloy Strips for Connectors and Our Development Strategy”, Kobe Steel Technical Report Vol. 54No. 1 (2004) p. 2-8 M. Motokori and two others, “Grain boundary type precipitation in Cu—Mg alloys”, Vol. 19 (1980) p. 115-124

  However, the phosphor bronze described in Patent Document 1 tends to have a high stress relaxation rate at high temperatures. Here, in a connector with a structure in which a male tab pushes up a female spring contact portion, if the stress relaxation rate at high temperature is high, the contact pressure decreases during use in a high temperature environment, resulting in poor conduction. There is a risk. For this reason, it could not be used in a high temperature environment such as around the engine room of an automobile.

  Further, in the Cu—Mg based alloys described in Non-Patent Document 2 and Patent Document 2, since a large amount of coarse intermetallic compounds containing Cu and Mg as main components are dispersed in the parent phase, bending processing is performed. Since these intermetallic compounds sometimes start from cracks and the like, there is a problem that electronic parts having complicated shapes cannot be formed.

  The present invention has been made in view of the above-described circumstances, and has high yield strength, high conductivity, excellent stress relaxation characteristics, excellent bending workability, such as terminals, connectors, relays, and lead frames. It aims at providing the copper alloy for electronic devices suitable for components for electronic devices, the manufacturing method of the copper alloy for electronic devices, the copper alloy plastic working material for electronic devices, and the electronic device parts.

  In order to solve this problem, the present inventors have conducted intensive research. As a result, in a work-hardening type copper alloy of a Cu-Mg supersaturated solid solution prepared by quenching a Cu-Mg alloy after forming a solution, it has a high yield strength. They obtained knowledge that they have high conductivity and excellent bending workability. Moreover, the knowledge that the improvement of an intensity | strength can be aimed at by adding 1 type, or 2 or more types of Ni, Si, Mn, Li, Ti, Fe, and Co in an appropriate amount was acquired. Furthermore, in the copper alloy which consists of this Cu-Mg supersaturated solid solution, the knowledge that it was possible to improve a stress relaxation-proof characteristic was acquired by implementing appropriate heat processing after finishing.

The present invention was made based on such findings, copper alloy for electronic devices of the present invention, the Mg, comprises in the range of less than 6.9 atomic% 3.3 atom% or more, a further N i , Si, Mn, Li, Ti, Fe, and Co in a total range of 0.01 atomic% to 3.0 atomic%, with the balance being Cu and inevitable impurities, scanning In an electron microscope observation, the average number of intermetallic compounds mainly composed of Cu and Mg having a particle diameter of 0.1 μm or more is 1 / μm ² or less, and 0.2% proof stress σ _0.2 is It is characterized by being 400 MPa or more .

As shown in the phase diagram of FIG. 1, the copper alloy for electronic equipment having the above-described configuration contains Mg in the range of 3.3 atomic% to 6.9 atomic% above the solid solution limit. In addition, in the observation with a scanning electron microscope, the average number of intermetallic compounds mainly composed of Cu and Mg having a particle size of 0.1 μm or more is 1 / μm ² or less. Precipitation of the intermetallic compound as a main component is suppressed, and the Mg—supersaturated solid solution in which the Mg is supersaturated in the matrix is formed.

The average number of intermetallic compounds mainly composed of Cu and Mg having a particle size of 0.1 μm or more was 10 × at a magnification of 50,000 times and a field of view of about 4.8 μm ² using a field emission scanning electron microscope. Calculate by observing the visual field.
In addition, the particle size of the intermetallic compound containing Cu and Mg as the main components is the major axis of the intermetallic compound (the length of the straight line that can be drawn the longest in the grain under the condition of not contacting the grain boundary in the middle) and the minor axis (major axis and It is defined as an average value of the length of a straight line that can be drawn longest in a direction that intersects at right angles and does not contact the grain boundary in the middle.

In a copper alloy composed of such a Cu-Mg supersaturated solid solution, a large amount of coarse intermetallic compounds mainly composed of Cu and Mg, which are the starting points of cracks, are not dispersed in the matrix phase, and bending workability Will be improved. Therefore, it is possible to mold electronic parts such as terminals, connectors, relays, and lead frames having complicated shapes.
In addition, since the stress relaxation resistance at high temperature is improved as compared with phosphor bronze, it can be used in a high temperature environment such as around the engine room of an automobile.

Further, since Mg is supersaturated, the strength can be improved by work hardening.
In the copper alloy for electronic devices of the present invention, at least one or more of Ni, Si, Mn, Li, Ti, Fe, Co is 0.01 atomic% or more and 3.0 atomic% or less in total. Since it is included in the range, it is possible to greatly improve the mechanical strength without greatly reducing the electrical conductivity.
Further, since the 0.2% proof stress σ _0.2 is 400 MPa or more, it is not easily plastically deformed, so that it is particularly suitable for electronic device parts such as terminals, connectors, relays, and lead frames.

Here, in the above-described copper alloy for electronic devices, the stress relaxation rate is preferably 50% or less at 1000C for 1000 hours.
In this case, since the stress relaxation rate is defined as described above, it is possible to suppress the occurrence of poor energization due to a decrease in contact pressure even when used in a high temperature environment. Therefore, it can be applied as a material for electronic device parts used in a high temperature environment such as an engine room.

The manufacturing method of the copper alloy for electronic devices of this invention is a manufacturing method of the copper alloy for electronic devices which produces the above-mentioned copper alloy for electronic devices, Comprising: Mg is 3.3 atomic% or more and 6.9 atomic% including within the following range, comprising in N i, Si, Mn, Li , Ti, Fe, 1 kind or range of 0.01 atomic% or more and 3.0 atomic% or less two or more in total of Co to further the balance Is heated to a temperature of 400 ° C. or more and 900 ° C. or less, and the heated copper material is heated at a cooling rate of 200 ° C./min or more at a cooling rate of 200 ° C./min or more. It is characterized by comprising a rapid cooling step for cooling to below ℃ and a processing step for plastic working the rapidly cooled copper material.

According to the method for producing a copper alloy for electronic equipment having this structure, the copper alloy is composed of a copper alloy containing Cu, Mg, and one or more of Ni, Si, Mn, Li, Ti, Fe, and Co. The solution of Mg can be formed by a heating process in which the copper material is heated to a temperature of 400 ° C. or higher and 900 ° C. or lower. Here, when the heating temperature is less than 400 ° C., solutionization is incomplete, and a large amount of intermetallic compounds mainly containing Cu and Mg may remain in the matrix phase. On the other hand, when the heating temperature exceeds 900 ° C., a part of the copper material becomes a liquid phase, and the structure and the surface state may become non-uniform. Therefore, the heating temperature is set in the range of 400 ° C to 900 ° C. In addition, in order to achieve such an effect reliably, it is preferable to make the heating temperature in a heating process into the range of 500 degreeC or more and 850 degrees C or less.
In addition, since the heated copper material is provided with a rapid cooling process that cools the heated copper material to 200 ° C. or less at a cooling rate of 200 ° C./min or more, an intermetallic compound containing Cu and Mg as main components in the course of cooling is provided. It becomes possible to suppress precipitation, and a copper raw material can be made into a Cu-Mg supersaturated solid solution.

  Furthermore, since the process which performs plastic processing with respect to the rapidly cooled copper raw material (Cu-Mg supersaturated solid solution) is provided, the strength improvement by work hardening can be aimed at. Here, the plastic working method is not particularly limited. For example, when the final form is a plate or strip, rolling, when wire or bar is drawn, extrusion, groove rolling, or forging or pressing is adopted when the shape is bulk. . The processing temperature is not particularly limited, but is preferably in the range of −200 ° C. to 200 ° C. which is cold or warm so that precipitation does not occur. The processing rate is appropriately selected so as to be close to the final shape. However, when work hardening is considered, it is preferably 20% or more, and more preferably 30% or more.

  Moreover, it is preferable that the above-mentioned copper alloy plastic working material for electronic devices is used as a copper material constituting components for electronic devices such as terminals, connectors, relays, and lead frames.

Furthermore, the electronic device component of the present invention is characterized by comprising the above-described copper alloy for electronic devices.
The electronic device parts (for example, terminals, connectors, relays, and lead frames) having this configuration are excellent in stress relaxation resistance and can be used even in a high temperature environment.

  According to the present invention, a copper alloy for electronic equipment having high proof stress, high electrical conductivity, excellent stress relaxation characteristics, excellent bending workability, and suitable for electronic equipment components such as terminals, connectors and relays, The manufacturing method of the copper alloy for apparatuses, the copper alloy plastic working material for electronic apparatuses, and the components for electronic apparatuses can be provided.

It is a Cu-Mg system phase diagram. It is a flowchart of the manufacturing method of the copper alloy for electronic devices which is this embodiment. It is a figure which shows the electron beam diffraction pattern of the deposit of the comparative example 7.

Embodiments of the present invention will be described below with reference to the drawings.
The component composition of the copper alloy for electronic devices according to the present embodiment includes Mg in the range of 3.3 atomic% to 6.9 atomic%, and at least Ni, Si, Mn, Li, Ti, Fe, Co. 1 type or 2 types or more are included in the range of 0.01 atomic% or more and 3.0 atomic% or less in total, and the remainder is substantially Cu and inevitable impurities.

And the copper alloy for electronic devices which is this embodiment WHEREIN: In scanning electron microscope observation, the average number of the intermetallic compound which has a particle size of 0.1 micrometer or more and which has Cu and Mg as a main component is 1 piece / micrometer < ² > or less. It is said that.
That is, the intermetallic compound which has Cu and Mg as the main components has hardly precipitated, Mg is solid-solved in the parent phase, and the copper alloy for electronic devices according to this embodiment is a Cu-Mg supersaturated solid solution. It is said that.

Moreover, in the copper alloy for electronic devices which is this embodiment, the stress relaxation rate shall be 50% or less in 150 degreeC and 1000 hours. Here, the stress relaxation rate was measured by applying stress by a method according to the cantilevered screw type of Japan Technical Standard JCBA-T309: 2004.
Furthermore, the copper alloy for electronic devices according to the present embodiment has a 0.2% proof stress σ _0.2 of 400 MPa or more.

(composition)
Mg is an element that has the effect of improving the strength and raising the recrystallization temperature without greatly reducing the electrical conductivity. Further, excellent bending workability can be obtained by dissolving Mg in the matrix.
Here, if the content of Mg is less than 3.3 atomic%, the effect cannot be achieved. On the other hand, if the Mg content exceeds 6.9 atomic%, an intermetallic compound containing Cu and Mg as main components remains when heat treatment is performed for solution treatment, and subsequent plastic working, etc. There is a risk of cracking.
For these reasons, the Mg content is set to 3.3 atomic% or more and 6.9 atomic% or less.

  Furthermore, when there is little content of Mg, intensity | strength will not fully improve. Moreover, since Mg is an active element, when it is added excessively, there is a possibility that Mg oxide generated by reacting with oxygen is involved during melt casting. Therefore, it is more preferable that the Mg content is in the range of 3.7 atomic% to 6.3 atomic%.

Ni, Si, Mn, Li, Ti, Fe, and Co are elements having an effect of further improving the strength of the copper alloy made into a Cu—Mg supersaturated solid solution.
Here, when the total content of at least one element of Ni, Si, Mn, Li, Ti, Fe, and Co is less than 0.1 atomic%, the effect cannot be achieved. On the other hand, if the total content of at least one element of Ni, Si, Mn, Li, Ti, Fe, and Co exceeds 3.0 atomic%, the conductivity is greatly reduced, which is not preferable. .
For these reasons, the total content of at least one element of Ni, Si, Mn, Li, Ti, Fe, and Co is within the range of 0.1 atomic% to 3.0 atomic%. Is set.

  Inevitable impurities include Sn, Zn, Al, Cr, Zr, Ag, B, P, Ca, Sr, Ba, Sc, Y, rare earth elements, Hf, V, Nb, Ta, Mo, W, Re, Ru, Os, Se, Te, Rh, Ir, Pd, Pt, Au, Cd, Ga, In, Ge, As, Sb, Tl, Pb, Bi, S, O, C, Be, N, H, Hg, etc. Is mentioned. These inevitable impurities are desirably 0.3% by mass or less in total. In particular, Sn is preferably less than 0.1% by mass and Zn is preferably less than 0.01% by mass. This is because when Sn is added in an amount of 0.1% by mass or more, precipitation of an intermetallic compound mainly composed of Cu and Mg is likely to occur, and when Zn is added in an amount of 0.01% by mass or more, melt casting is performed. This is because fumes are generated in the process and adhere to the furnace and mold members to deteriorate the surface quality of the ingot and the stress corrosion cracking resistance.

(Organization)
In the copper alloy for electronic devices according to this embodiment, as a result of observation with a scanning electron microscope, the average number of intermetallic compounds mainly composed of Cu and Mg having a particle diameter of 0.1 μm or more is 1 / μm ^2. It is as follows. That is, almost no intermetallic compound mainly composed of Cu and Mg is precipitated, and Mg is dissolved in the matrix.
Here, when the solution formation is incomplete, or when an intermetallic compound mainly composed of Cu and Mg is precipitated after solution formation, a large amount of intermetallic compounds exist in a large size. It becomes the starting point of cracking, cracking occurs during plastic working, and bending workability is greatly deteriorated.

As a result of investigating the structure, when the intermetallic compound containing Cu and Mg as main components having a particle size of 0.1 μm or more is 1 / μm ² or less in the alloy, that is, the intermetallic compound containing Cu and Mg as main components. When there is no or a small amount, good bending workability can be obtained.
Furthermore, in order to ensure that the above-described effects are achieved, the number of intermetallic compounds mainly composed of Cu and Mg having a particle diameter of 0.05 μm or more is 1 / μm ² or less in the alloy. More preferred.

The average number of intermetallic compounds mainly composed of Cu and Mg was observed using a field emission scanning electron microscope with 10 fields of view at a magnification of 50,000 times and a field of view of about 4.8 μm ^2. The average value is calculated.
In addition, the particle size of the intermetallic compound containing Cu and Mg as the main components is the major axis of the intermetallic compound (the length of the straight line that can be drawn the longest in the grain under the condition of not contacting the grain boundary in the middle) and the minor axis (major axis and It is defined as an average value of the length of a straight line that can be drawn longest in a direction that intersects at right angles and does not contact the grain boundary in the middle.

Here, the intermetallic compound containing Cu and Mg as main components has a crystal structure represented by the chemical formula MgCu ₂ , prototype MgCu ₂ , Pearson symbol cF24, and space group number Fd-3m.

(Stress relaxation rate)
In the copper alloy for electronic devices according to this embodiment, as described above, the stress relaxation rate is 50% or less at 150 ° C. for 1000 hours.
When the stress relaxation rate under these conditions is low, permanent deformation can be suppressed to a small level even when used in a high temperature environment, and a decrease in contact pressure can be suppressed. Therefore, the copper alloy for electronic devices according to the present embodiment can be applied as a terminal used in a high temperature environment such as around the engine room of an automobile.
The stress relaxation rate is preferably 30% or less at 150 ° C. and 1000 hours, and more preferably 20% or less at 150 ° C. and 1000 hours.

Next, the manufacturing method of the copper alloy for electronic devices which is this embodiment configured as above will be described with reference to the flowchart shown in FIG.
In the following manufacturing method, when rolling is used as the processing step, the processing rate corresponds to the rolling rate.

(Melting / Casting Process S01)
First, the above-described elements are added to a molten copper obtained by melting a copper raw material to adjust the components, thereby producing a molten copper alloy. In addition, Mg simple substance, Cu-Mg master alloy, etc. can be used for addition of Mg. Moreover, you may melt | dissolve the raw material containing Mg with a copper raw material. Moreover, you may use the recycling material and scrap material of this alloy.
Here, the molten copper is preferably so-called 4NCu having a purity of 99.99% by mass or more. Further, in the melting step, it is preferable to use a vacuum furnace or an atmosphere furnace having an inert gas atmosphere or a reducing atmosphere in order to suppress oxidation of Mg.
Then, the copper alloy molten metal whose components are adjusted is poured into a mold to produce an ingot. In consideration of mass production, it is preferable to use a continuous casting method or a semi-continuous casting method.

(Heating step S02)
Next, heat treatment is performed for homogenization and solution of the obtained ingot. Inside the ingot, there are intermetallic compounds and the like mainly composed of Cu and Mg generated by the concentration of Mg by segregation during the solidification process. Therefore, in order to eliminate or reduce these segregation and intermetallic compounds, etc., heat treatment is performed to heat the ingot to 400 ° C. or more and 900 ° C. or less, so that Mg can be uniformly diffused in the ingot. Mg is dissolved in the matrix. The heating step S02 is preferably performed in a non-oxidizing or reducing atmosphere.
Here, when the heating temperature is less than 400 ° C., solutionization is incomplete, and a large amount of intermetallic compounds mainly containing Cu and Mg may remain in the matrix phase. On the other hand, when the heating temperature exceeds 900 ° C., a part of the copper material becomes a liquid phase, and the structure and the surface state may become non-uniform. Therefore, the heating temperature is set in the range of 400 ° C. or higher and 900 ° C. or lower. More preferably, it is 500 degreeC or more and 850 degrees C or less, More preferably, you may be 520 degreeC or more and 800 degrees C or less.

(Rapid cooling step S03)
And the copper raw material heated to 400 degreeC or more and 900 degrees C or less in heating process S02 is cooled by the cooling rate of 200 degrees C / min or more to the temperature of 200 degrees C or less. This rapid cooling step S03 suppresses the precipitation of Mg dissolved in the matrix as an intermetallic compound containing Cu and Mg as main components. In observation with a scanning electron microscope, Cu having a particle diameter of 0.1 μm or more is suppressed. The average number of intermetallic compounds containing Mg and Mg as main components can be 1 / μm ² or less. That is, the copper material can be a Cu—Mg supersaturated solid solution.
In addition, in order to increase the efficiency of roughing and make the structure uniform, it is possible to perform a hot working after the heating step S02 and perform the rapid cooling step S03 after the hot working. In this case, there is no particular limitation on the processing method, for example, rolling when the final form is a plate or strip, drawing, extruding, groove rolling, etc. for a wire or bar, forging or pressing for a bulk shape. Can be adopted.

(Intermediate processing step S04)
The copper material that has undergone the heating step S02 and the rapid cooling step S03 is cut as necessary, and surface grinding is performed as necessary to remove the oxide film and the like generated in the heating step S02, the rapid cooling step S03, and the like. Then, plastic working is performed into a predetermined shape.
In addition, the temperature condition in the intermediate processing step S04 is not particularly limited, but it is preferable to be within a range of −200 ° C. to 200 ° C. which is cold or warm processing. The processing rate is appropriately selected so as to approximate the final shape. However, in order to reduce the number of intermediate heat treatment steps S05 until the final shape is obtained, the processing rate is preferably set to 20% or more. Moreover, it is more preferable that the processing rate is 30% or more. The processing method is not particularly limited, but when the final shape is a plate or strip, it is preferable to employ rolling. It is preferable to employ extrusion or groove rolling in the case of a wire or bar, and forging or pressing in the case of a bulk shape. Further, S02 to S04 may be repeated for thorough solution.

(Intermediate heat treatment step S05)
After the intermediate processing step S04, heat treatment is performed for the purpose of thorough solution, recrystallization structure, or softening for improving workability.
The heat treatment method is not particularly limited, but the heat treatment is preferably performed in a non-oxidizing atmosphere or a reducing atmosphere under conditions of 400 ° C. to 900 ° C. More preferably, it is 500 degreeC or more and 850 degrees C or less, More preferably, you may be 520 degreeC or more and 800 degrees C or less.
Note that the intermediate processing step S04 and the intermediate heat treatment step S05 may be repeatedly performed.

Here, in the intermediate heat treatment step S05, the copper material heated to 400 ° C. or more and 900 ° C. or less is cooled to a temperature of 200 ° C. or less at a cooling rate of 200 ° C./min or more. Such rapid cooling suppresses the precipitation of Mg dissolved in the matrix as an intermetallic compound containing Cu and Mg as main components. The average number of intermetallic compounds mainly composed of Cu and Mg of 1 μm or more can be 1 / μm ² or less. That is, the copper material can be a Cu—Mg supersaturated solid solution.

(Finishing process S06)
The copper material after the intermediate heat treatment step S05 is finished into a predetermined shape. The temperature condition in the finishing process S06 is not particularly limited, but it is preferably performed at room temperature. The processing rate is appropriately selected so as to approximate the final shape, but is preferably 20% or more in order to improve the strength by work hardening. Also. In order to further improve the strength, the processing rate is more preferably 30% or more. This plastic working method is not particularly limited, but when the final shape is a plate or strip, it is preferable to employ rolling. It is preferable to employ extrusion or groove rolling in the case of a wire or bar, and forging or pressing in the case of a bulk shape.

(Finish heat treatment step S07)
Next, a finishing heat treatment is performed on the plastic workpiece obtained in the finishing step S06 in order to improve the stress relaxation resistance and perform low-temperature annealing hardening or to remove residual strain. .
The heat treatment temperature is preferably in the range of 200 ° C to 800 ° C. In the finish heat treatment step S07, it is necessary to set heat treatment conditions (temperature, time, cooling rate) so that solutionized Mg does not precipitate. For example, it is preferable to set at 250 ° C. for about 10 seconds to 24 hours, 300 ° C. for about 5 seconds to 4 hours, and 500 ° C. for about 0.1 seconds to 60 seconds. This heat treatment is preferably performed in a non-oxidizing atmosphere or a reducing atmosphere.

Moreover, it is preferable that a cooling method cools the said copper raw material heated, such as water quenching, to 200 degrees C or less with the cooling rate of 200 degrees C / min or more. Such rapid cooling suppresses the precipitation of Mg dissolved in the matrix as an intermetallic compound containing Cu and Mg as main components. The average number of intermetallic compounds mainly composed of Cu and Mg of 1 μm or more can be 1 / μm ² or less. That is, the copper material can be a Cu—Mg supersaturated solid solution.
Furthermore, the above-described finishing processing step S06 and finishing heat treatment step S07 may be repeated. The intermediate heat treatment step and the finish heat treatment step can be distinguished by whether or not the purpose is to recrystallize the structure after plastic working in the intermediate processing step or the finishing step.

Thus, the copper alloy for electronic devices which is this embodiment is produced. And as for the copper alloy for electronic devices which is this embodiment, 0.2% yield strength (sigma) _0.2 shall be 400 Mpa or more.
Furthermore, according to the finish heat treatment step S07, the copper alloy for electronic devices according to the present embodiment has a stress relaxation rate of 50% or less at 150 ° C. for 1000 hours.

According to the copper alloy for electronic devices of the present embodiment configured as described above, Mg is included in the range of 3.3 atomic% to 6.9 atomic%, and at least Ni, Si, Mn, Li , Ti, Fe, and Co in a total range of 0.01 atomic percent to 3.0 atomic percent, with the balance being substantially Cu and inevitable impurities, observed by scanning electron microscope , The average number of intermetallic compounds mainly composed of Cu and Mg having a particle size of 0.1 μm or more is 1 piece / μm ² or less.

That is, the copper alloy for electronic devices according to this embodiment is a Cu—Mg supersaturated solid solution in which Mg is supersaturated in the matrix.
In a copper alloy composed of such a Cu-Mg supersaturated solid solution, a large amount of coarse intermetallic compounds mainly composed of Cu and Mg, which are the starting points of cracks, are not dispersed in the matrix phase, and bending workability is improved. Will improve. Therefore, it is possible to mold electronic device parts such as terminals, connectors, relays, and lead frames having complicated shapes.
Furthermore, since Mg is super-saturated, the strength is improved by work hardening, and a relatively high strength can be obtained.

  Moreover, the copper alloy for electronic devices which is this embodiment is 0.01 atomic% or more and 3.0 atomic% or less in total of at least one or more of Ni, Si, Mn, Li, Ti, Fe, and Co. Therefore, the mechanical strength can be greatly improved without greatly reducing the electrical conductivity.

  And in the copper alloy for electronic devices which is this embodiment, since the stress relaxation rate shall be 50% or less in 1000 degreeC and 1000 hours, even if it is a case where it is used also in a high temperature environment, it supplies with electricity by a contact pressure fall. The occurrence of defects can be suppressed. Therefore, it can be applied as a material for electronic device parts used in a high temperature environment such as an engine room.

Further, in the copper alloy for electronic devices according to the present embodiment, since 0.2% proof stress σ _0.2 is 400 MPa or more, it is not easily plastically deformed, so that terminals, connectors, relays, leads It is particularly suitable for electronic parts of frames.

According to the method for manufacturing a copper alloy for electronic devices according to the present embodiment, the solution of Mg is formed by heating step S02 in which the ingot or plastic work material having the above composition is heated to a temperature of 400 ° C. or higher and 900 ° C. or lower. It can be carried out.
Further, since the ingot or plastic work material heated to 400 ° C. or more and 900 ° C. or less by the heating step S02 is provided with a rapid cooling step S03 for cooling to 200 ° C. or less at a cooling rate of 200 ° C./min or more, It becomes possible to suppress the precipitation of intermetallic compounds containing Cu and Mg as main components in the course of cooling, and the ingot or plastic working material after quenching can be made into a Cu-Mg supersaturated solid solution.

Furthermore, since the intermediate processing step S04 for performing plastic working on the quenching material (Cu—Mg supersaturated solid solution) is provided, a shape close to the final shape can be easily obtained.
In addition, since the intermediate heat treatment step S05 is provided after the intermediate processing step S04 for the purpose of thorough solution, recrystallization structure or softening for improving the workability, the characteristics and workability should be improved. Can do.
In addition, in the intermediate heat treatment step S05, the copper material heated to 400 ° C. or more and 900 ° C. or less is cooled to 200 ° C. or less at a cooling rate of 200 ° C./min or more. It becomes possible to suppress precipitation of the intermetallic compound as a main component, and the copper material after quenching can be made into a Cu-Mg supersaturated solid solution.

And in the manufacturing method of the copper alloy for electronic devices which is this embodiment, after the finishing process S06 for carrying out the strength improvement by work hardening and plastic processing to a predetermined shape, improvement of a stress relaxation characteristic and low temperature annealing hardening In order to perform the heat treatment or to remove the residual strain, the finish heat treatment step S07 is provided, so that the stress relaxation rate can be reduced to 50% or less at 150 ° C. for 1000 hours. Further, it is possible to further improve the mechanical characteristics.
In the finish heat treatment step S07, heat treatment is performed in the range of 200 ° C. or higher and 800 ° C. or lower, and then the heated copper material is cooled to 200 ° C. or lower at a cooling rate of 200 ° C./min or higher. Therefore, it becomes possible to suppress the precipitation of intermetallic compounds mainly composed of Cu and Mg during the cooling process, and the copper alloy for electronic equipment after the finish heat treatment step S07 is made a Cu-Mg supersaturated solid solution. Can do.

As mentioned above, although the manufacturing method of the copper alloy for electronic devices and the copper alloy for electronic devices which is embodiment of this invention was demonstrated, this invention is not limited to this, The range which does not deviate from the technical idea of the invention It can be changed as appropriate.
For example, in the above-described embodiment, an example of a method for manufacturing a copper alloy for electronic devices has been described. However, the manufacturing method is not limited to this embodiment, and an existing manufacturing method may be selected as appropriate. Good.

Below, the result of the confirmation experiment performed in order to confirm the effect of this invention is demonstrated.
A copper raw material made of oxygen-free copper (ASTM B152 C10100) having a purity of 99.99% by mass or more was prepared, charged in a high-purity graphite crucible, and melted at high frequency in an atmosphere furnace having an Ar gas atmosphere. . Various additive elements were added to the obtained molten copper to prepare the component compositions shown in Tables 1 and 2, and poured into a carbon mold to produce an ingot. The size of the ingot was about 20 mm thick x about 20 mm wide x about 100 to 120 mm long.

  The obtained ingot was subjected to a heating process in which heating was performed for 4 hours under the temperature conditions shown in Table 1 in an Ar gas atmosphere, followed by water quenching.

  The ingot after the heat treatment was cut and surface grinding was performed to remove the oxide film. Thereafter, intermediate rolling was performed at room temperature at a rolling rate described in Table 1. And the intermediate heat processing was implemented in the salt bath on the conditions of the temperature described in Table 1 with respect to the obtained strip. Thereafter, water quenching was performed.

Next, finish rolling was performed at the rolling rates shown in Table 1 to produce strips having a thickness of 0.25 mm and a width of about 20 mm.
And after finishing rolling, finishing heat processing was implemented in the salt bath on the conditions shown in the table | surface, and then water quenching was implemented and the strip for characteristic evaluation was created.

(Processability evaluation)
As an evaluation of workability, the presence or absence of ear cracks during the cold rolling described above was observed. The case where no or almost no ear cracks were visually observed was ◎, the case where a small ear crack of less than 1 mm in length occurred was ○, the case where an ear crack of 1 mm or more and less than 3 mm occurred was Δ, and a length of 3 mm The case where the above-mentioned big ear crack generate | occur | produced was made into x, and what was fractured | ruptured in the middle of rolling due to the ear crack was made into xx.
In addition, the length of an ear crack is the length of the ear crack which goes to the width direction center part from the width direction edge part of a rolling material.

Using the above-mentioned strips for property evaluation, the mechanical properties and conductivity were measured.
(Mechanical properties)
A No. 13B test piece defined in JIS Z 2201 was taken from the strip for characteristic evaluation, and 0.2% proof stress σ _0.2 was measured by an offset method of JIS Z 2241. The test piece was collected in a direction parallel to the rolling direction.

(conductivity)
A test piece having a width of 10 mm and a length of 60 mm was taken from the strip for characteristic evaluation, and the electrical resistance was determined by a four-terminal method. Moreover, the dimension of the test piece was measured using the micrometer, and the volume of the test piece was calculated. And electrical conductivity was computed from the measured electrical resistance value and volume. In addition, the test piece was extract | collected so that the longitudinal direction might become parallel with the rolling direction of the strip for characteristic evaluation.

(Stress relaxation characteristics)
In the stress relaxation resistance test, stress was applied by a method according to the cantilever screw method of Japan Copper and Brass Association Technical Standard JCBA-T309: 2004, and the residual stress ratio after holding at a temperature of 150 ° C. for a predetermined time was measured. .
The test piece (width 10 mm) was sampled so that its longitudinal direction was parallel to the rolling direction of the strip for property evaluation.
The initial deflection displacement was set to 2 mm and the span length was adjusted so that the maximum surface stress of the test piece was 80% of the proof stress. The maximum surface stress is determined by the following equation.
Maximum surface stress (MPa) = 1.5 Etδ ₀ / L _S ²
However,
E: Deflection coefficient (MPa)
t: sample thickness (t = 0.25 mm)
δ ₀ : Initial deflection displacement (2 mm)
L _s : Span length (mm)
It is.
The residual stress rate was measured from the bending habit after holding for 1000 hours at a temperature of 150 ° C., and the stress relaxation rate was evaluated. The stress relaxation rate was calculated using the following formula.
Stress relaxation rate (%) = (δ _t / δ ₀ ) × 100
However,
δ _t : Permanent deflection displacement after holding for 1000 h at 150 ° C. (mm) −Permanent deflection displacement after holding for 24 h at room temperature (mm)
δ ₀ : Initial deflection displacement (mm)
It is.

(Bending workability)
Bending was performed in accordance with four test methods of Japan Copper and Brass Association Technical Standard JCBA-T307: 2007.
A plurality of test pieces having a width of 10 mm and a length of 30 mm are taken from the strip for characteristic evaluation so that the rolling direction and the longitudinal direction of the test piece are parallel to each other, and a W type having a bending angle of 90 degrees and a bending radius of 0.25 mm. The W-bending test was performed using the jig.
Then, visually check the outer periphery of the bent portion, x if it breaks, △ if only a portion breaks, ◯ if it does not break and only a minute crack occurs, rupture or a minute crack Judgment was made as ◎ when the case could not be confirmed.

(Tissue observation)
Mirror polishing and ion etching were performed on the rolled surface of each sample. In order to confirm the precipitation state of the intermetallic compound containing Cu and Mg as main components, the observation was performed using a FE-SEM (Field Emission Scanning Electron Microscope) with a 10,000 × field of view (about 120 μm ² / field of view). .
Next, in order to investigate the density of intermetallic compounds mainly composed of Cu and Mg (pieces / μm ² ), a 10,000 times field of view (about 120 μm ² / field of view) where the precipitation state of intermetallic compounds is not unique In this region, 10 fields of view (about 4.8 μm ² / field of view) were taken at a magnification of 50,000 times. As for the particle size of the intermetallic compound, the major axis of the intermetallic compound (the length of the straight line that can be drawn the longest in the grain without contact with the grain boundary in the middle) and the minor axis (in the direction perpendicular to the major axis, the grain in the middle The average value of the length of the straight line that can be drawn the longest under conditions that do not contact the boundary). And the density (piece / micrometer < ² >) of the intermetallic compound which has Cu and Mg as a main component with a particle size of 0.1 micrometer or more was calculated | required.

  Tables 1 and 2 show the conditions and evaluation results.

In Comparative Example 1 in which the Mg content was lower than the range of the present invention, the 0.2% yield strength was as low as 392 MPa or less.
In Comparative Examples 2 and 3 in which the Mg content is higher than the range of the present invention, large ear cracks occurred during intermediate rolling, and it was impossible to perform subsequent characteristic evaluation.
In Comparative Example 4 in which the total content of one or more of Ni, Si, Mn, Li, Ti, Fe, and Co exceeded 3.0 atomic%, the conductivity was as low as 10%. .
Furthermore, in the comparative examples 5 and 6 in which the composition is within the range of the present invention but the conductivity and the number of intermetallic compounds mainly composed of Cu and Mg are out of the range of the present invention, the bending workability is inferior. It is confirmed that

  Furthermore, in the conventional examples 1 and 2 made of copper alloys containing Sn and P, so-called phosphor bronze, the electrical conductivity was low and the stress relaxation rate exceeded 50%.

On the other hand, in Example 1-9 of the present invention, the 0.2% proof stress is as high as 580 MPa or more. Also, the stress relaxation rate is as low as 48% or less. Furthermore, the electrical conductivity is also set to 19% or more, and it is confirmed that it is higher than that of the conventional phosphor bronze.
In addition, it is confirmed that Example 1-8 of this invention which performed finish heat processing has improved the stress relaxation rate compared with Example 9 of this invention which did not implement finish heat processing.

Here, the electron diffraction pattern of the precipitate confirmed in Comparative Example 7 is shown in FIG. This electron diffraction pattern shows the electron beam incident direction of MgCu ₂ with Pearson symbol cF24, space group number Fd-3m (227), and lattice constant a = b = c = 0.7034 nm.
And corresponds to the “intermetallic compound containing Cu and Mg as main components” in the present invention.

  And in this invention example 1-9, the intermetallic compound which has Cu and Mg as a main component mentioned above is not observed, but it is set as the Cu-Mg supersaturated solid solution in which Mg was supersaturated in the mother phase. It is.

  From the above, according to the example of the present invention, it has high proof stress, high electrical conductivity, excellent stress relaxation property, excellent bending workability, and is suitable for electronic device parts such as terminals, connectors and relays. It was confirmed that a copper alloy for equipment can be provided.

Claims (5)

The mg, 3.3 containing in atomic% or more 6.9 atomic% or less, further to N i, Si, Mn, Li , Ti, Fe, 0.01 atom in total of one or more of Co % To 3.0 atomic%, with the balance being Cu and inevitable impurities,
In observation with a scanning electron microscope, the average number of intermetallic compounds mainly composed of Cu and Mg having a particle size of 0.1 μm or more is 1 / μm ² or less ,
A copper alloy for electronic equipment, characterized in that 0.2% proof stress σ _0.2 is 400 MPa or more . In the copper alloy for electronic devices according to claim 1,
A copper alloy for electronic equipment, wherein a stress relaxation rate is 50% or less at 1000C for 1000 hours. It is a manufacturing method of the copper alloy for electronic devices which produces the copper alloy for electronic devices of Claim 1 or Claim 2 ,
The mg, 3.3 containing in atomic% or more 6.9 atomic% or less, further to N i, Si, Mn, Li , Ti, Fe, 0.01 atom in total of one or more of Co A heating step of heating a copper material having a composition that is included in a range of not less than% and not more than 3.0 atomic%, the balance being Cu and inevitable impurities, to a temperature of not less than 400 ° C. and not more than 900 ° C .;
A rapid cooling step of cooling the heated copper material to 200 ° C. or less at a cooling rate of 200 ° C./min or more;
A processing step for plastic processing of a rapidly cooled copper material;
The manufacturing method of the copper alloy for electronic devices characterized by the above-mentioned. The copper alloy for electronic equipment according to claim 1 or claim 2 ,
A copper alloy plastic working material for electronic equipment, characterized in that it is used as a copper material constituting electronic equipment parts such as terminals, connectors, relays, and lead frames. An electronic device component comprising the copper alloy for an electronic device according to claim 1 .